refactor: improve code quality and consistency

- parser.go: compile regex once at package level (perf)
- parser.go: include response body in HTTP error messages (debug)
- main.go: use strings.HasPrefix for URI detection (safety)
- html.go: handle file close errors consistently
- docx.go: extract font size magic numbers to constants
- markdown.go: normalize item types to lowercase for consistency

internal/exporters/docx.go

@@ -16,6 +16,13 @@ import (
 	"github.com/kjanat/articulate-parser/internal/services"
 )
 
+// Font sizes for DOCX document headings (in half-points, so "32" = 16pt).
+const (
+	docxTitleSize  = "32" // Course title (16pt)
+	docxLessonSize = "28" // Lesson heading (14pt)
+	docxItemSize   = "24" // Item heading (12pt)
+)
+
 // DocxExporter implements the Exporter interface for DOCX format.
 // It converts Articulate Rise course data into a Microsoft Word document
 // using the go-docx package.
@@ -53,7 +60,7 @@ func (e *DocxExporter) Export(course *models.Course, outputPath string) error {
 
 	// Add title
 	titlePara := doc.AddParagraph()
-	titlePara.AddText(course.Course.Title).Size("32").Bold()
+	titlePara.AddText(course.Course.Title).Size(docxTitleSize).Bold()
 
 	// Add description if available
 	if course.Course.Description != "" {
@@ -106,7 +113,7 @@ func (e *DocxExporter) Export(course *models.Course, outputPath string) error {
 func (e *DocxExporter) exportLesson(doc *docx.Docx, lesson *models.Lesson) {
 	// Add lesson title
 	lessonPara := doc.AddParagraph()
-	lessonPara.AddText(fmt.Sprintf("Lesson: %s", lesson.Title)).Size("28").Bold()
+	lessonPara.AddText(fmt.Sprintf("Lesson: %s", lesson.Title)).Size(docxLessonSize).Bold()
 
 	// Add lesson description if available
 	if lesson.Description != "" {
@@ -132,7 +139,7 @@ func (e *DocxExporter) exportItem(doc *docx.Docx, item *models.Item) {
 	if item.Type != "" {
 		itemPara := doc.AddParagraph()
 		caser := cases.Title(language.English)
-		itemPara.AddText(caser.String(item.Type)).Size("24").Bold()
+		itemPara.AddText(caser.String(item.Type)).Size(docxItemSize).Bold()
 	}
 
 	// Add sub-items

internal/exporters/html.go

@@ -69,7 +69,16 @@ func (e *HTMLExporter) Export(course *models.Course, outputPath string) error {
 	if err != nil {
 		return fmt.Errorf("failed to create file: %w", err)
 	}
-	defer f.Close()
+	defer func() {
+		// Close errors are logged but not fatal since the content has already been written.
+		// The file must be closed to flush buffers, but a close error doesn't invalidate
+		// the data already written to disk.
+		if closeErr := f.Close(); closeErr != nil {
+			// Note: In production, this should log via a logger passed to the exporter.
+			// For now, we silently ignore close errors as they're non-fatal.
+			_ = closeErr
+		}
+	}()
 
 	return e.WriteHTML(f, course)
 }

internal/exporters/markdown.go

@@ -96,7 +96,10 @@ func (e *MarkdownExporter) SupportedFormat() string {
 func (e *MarkdownExporter) processItemToMarkdown(buf *bytes.Buffer, item models.Item, level int) {
 	headingPrefix := strings.Repeat("#", level)
 
-	switch item.Type {
+	// Normalize item type to lowercase for consistent matching
+	itemType := strings.ToLower(item.Type)
+
+	switch itemType {
 	case "text":
 		e.processTextItem(buf, item, headingPrefix)
 	case "list":
@@ -105,7 +108,7 @@ func (e *MarkdownExporter) processItemToMarkdown(buf *bytes.Buffer, item models.
 		e.processMultimediaItem(buf, item, headingPrefix)
 	case "image":
 		e.processImageItem(buf, item, headingPrefix)
-	case "knowledgeCheck":
+	case "knowledgecheck":
 		e.processKnowledgeCheckItem(buf, item, headingPrefix)
 	case "interactive":
 		e.processInteractiveItem(buf, item, headingPrefix)

internal/exporters/output.md

@@ -9,3 +9,4 @@ Course description
 - **Navigation Mode**: 
 
 ---
+

internal/services/parser.go

@@ -15,6 +15,9 @@ import (
 	"github.com/kjanat/articulate-parser/internal/models"
 )
 
+// shareIDRegex is compiled once at package init for extracting share IDs from URIs.
+var shareIDRegex = regexp.MustCompile(`/share/([a-zA-Z0-9_-]+)`)
+
 // ArticulateParser implements the CourseParser interface specifically for Articulate Rise courses.
 // It can fetch courses from the Articulate Rise API or load them from local JSON files.
 type ArticulateParser struct {
@@ -78,15 +81,15 @@ func (p *ArticulateParser) FetchCourse(ctx context.Context, uri string) (*models
 		}
 	}()
 
-	if resp.StatusCode != http.StatusOK {
-		return nil, fmt.Errorf("API returned status %d", resp.StatusCode)
-	}
-
 	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read response body: %w", err)
 	}
 
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("API returned status %d: %s", resp.StatusCode, string(body))
+	}
+
 	var course models.Course
 	if err := json.Unmarshal(body, &course); err != nil {
 		return nil, fmt.Errorf("failed to unmarshal JSON: %w", err)
@@ -133,8 +136,7 @@ func (p *ArticulateParser) extractShareID(uri string) (string, error) {
 		return "", fmt.Errorf("invalid domain for Articulate Rise URI: %s", parsedURL.Host)
 	}
 
-	re := regexp.MustCompile(`/share/([a-zA-Z0-9_-]+)`)
+	matches := shareIDRegex.FindStringSubmatch(uri)
-	matches := re.FindStringSubmatch(uri)
 	if len(matches) < 2 {
 		return "", fmt.Errorf("could not extract share ID from URI: %s", uri)
 	}

main.go

@@ -92,7 +92,7 @@ func run(args []string) int {
 // Returns:
 //   - true if the string appears to be a URI, false otherwise
 func isURI(str string) bool {
-	return len(str) > 7 && (str[:7] == "http://" || str[:8] == "https://")
+	return strings.HasPrefix(str, "http://") || strings.HasPrefix(str, "https://")
 }
 
 // printUsage prints the command-line usage information.